How do microorganisms affect humus and thereby soil health?

Microorganisms present in the soil can transform organic matter to other substances which can be useful. The organic matter serves as their food. These microorganisms when present in the soil are responsible for improving the health of the soil. Microorganisms consume their food from the soil and in return they release certain substances that are nutrients for the soil thus increasing soil health.

This is giving me a headache i have asked others and they don’t know it either